Aspirin use and incident stroke in the cardiovascular health study. CHS Collaborative Research Group

Antithrombotic therapy in end-stage renal disease

The delicate balance of risk vs. benefit of using antiplatelet and antithrombotic agents in the general population is well established. The decision to use these agents in the end stage renal disease (ESRD) population remains complex and difficult. The concomitant association of a prothombotic state with high risk of bleeding in the ESRD population requires individualization and careful clinical judgment before implementing such therapy. There remains a paucity of clinical trials and lack of substantial evidence in literature for safe and effective use of antithrombotic drugs in patients with advanced chronic kidney disease. The current review summarizes the pros and cons of using antiplatelet and antithrombotic agents in primary and secondary prevention of cardiovascular events, evaluate the risks with routine use of anticoagulation for cerebrovascular stroke prevention with nonvalvular atrial fibrillation and role of newer oral anticoagulants as alternate agents in the dialysis population.

A Review of Cardiovascular Disease and Treatment Differences in Women

Cardiovascular disease (CVD) is a significant health care problem in the United States today. Women comprise an increasing component of the population affected by this disease. Recent reports have suggested that women are not enrolled in adequate numbers in major clinical studies and, furthermore, are less likely to receive treatment as recommended by evidence-based medicine guidelines. Historical differences in the investigation and treatment of cardiovascular disease between women and men are discussed. Reasons for differences in study enrollment of women are proposed. Efforts by the Food and Drug Administration to improve data collection in women are outlined. The influence of major risk factors, including smoking, hyperlipidemia, and hypertension, on development and progression of CVD is addressed. Major trials of CVD and heart failure are examined. An assessment of progress toward a goal of gender treatment equality is made.

Systemic thromboembolic adverse events in patients treated with intravitreal anti-VEGF drugs for neovascular age-related macular degeneration: an overview

INTRODUCTION

Anti-VEGF therapy improved the quality of life for millions of patients suffering from wet age-related macular degeneration (wet-AMD); unfortunately, this therapy involves multiple injections over many years. The administration of anti-VEGF can overcome the blood-retinal barrier with agents entering the systemic circulation and causing a significant decrease in VEGF serum concentration. Although circulating VEGF protects the integrity and patency of vessels, prolonged anti-VEGF treatment has the potential to increase the risk of thromboembolic events.

AREAS COVERED

In this review, we discuss the safety data from recent trials involving available anti-VEGF drugs.

EXPERT OPINION

During the 2 years of follow-up in the relevant clinical trials, the rates of serious adverse events such as stroke, heart attack and death were similar for patients treated with different anti-VEGF drugs. Moreover the arterial thrombotic risk appears sufficiently low when compared with the natural incidence of arterial thrombotic events in this category of elderly patients and acceptably balanced against the advantage of improved vision. Since the use of these drugs is likely to become increasingly widespread and prolonged, it is desirable that the scientific community improves the pharmacovigilance program on all anti-VEGF drugs, expanding knowledge with studies that compares head to head all four compounds belonging to anti-VEGF armamentarium.

Plasma free fatty acids and risk of stroke in the Cardiovascular Health Study

BACKGROUND

Although free fatty acids have been positively associated with risk factors for stroke, the role of plasma free fatty acids in the development of stroke has not been elucidated in older adults.

AIMS

We sought to examine the association between plasma free fatty acids and incident stroke.

METHODS

Prospective cohort of 4369 men and women≥65 years of age in the Cardiovascular Health Study. Plasma levels of free fatty acids were measured at the 1992-1993 examination and stroke events were adjudicated by a committee of experts including neurologists and neuroradiologists. Cox regression was used to estimate the relative risk of stroke associated with free fatty acids concentrations.

RESULTS

The average age among participants was 75±5·2 years. During a median follow-up of 11·4 years, 732 incident strokes occurred. The crude incidence rates of stroke were 14·5, 14·9, and 17·6 per 1000 person-years across increasing tertiles of plasma free fatty acids. The adjusted hazard ratio (95% confidence interval) for incident stroke was 1·05 (0·97-1·14) per standard deviation increase in plasma free fatty acids. Restriction to ischemic stroke did not alter the results [hazard ratio (95% confidence interval): 1·04 (0·96-1·14) per standard deviation higher free fatty acids], and there was no effect modification by adiposity (P interaction=0·18) or by diabetes (P interaction=0·15).

CONCLUSION

Our data did not show an association of plasma free fatty acids with incident stroke among community dwelling older adults.

Aspirin and clopidogrel for prevention of ischemic stroke

This review examines the role of platelets in ischemic stroke, platelet activation mechanisms, aspirin's rise as an antithrombotic agent, clopidogrel's appearance on the stage, a possible role for combination therapy, antiplatelet resistance, practical considerations, and future directions. Reviewed in this chapter are issues central to optimal antiplatelet therapy: efficacy, safety, resistance, and biochemical/laboratory testing. Current guidelines do not recommend combination aspirin and clopidogrel use, however recent research indicates dual antiplatelet therapy with combined aspirin and clopidogrel may have specific roles in secondary prevention of ischemic stroke. A cautious and analytical interpretation of the literature is advised before application of this knowledge to clinical practice. The best recommendation at this time is to follow the published guidelines for secondary prevention of ischemic stroke.

Acetylsalicylic acid for primary prevention of cardiovascular diseases in older patients with diabetes: do the benefits overcome the risks?

Cardiovascular diseases (CVDs) represent a huge health burden for older patients with diabetes. Acetylsalicylic acid (ASA) has long been used as a cardioprotective agent in primary and secondary prevention of CVD. However, there are important issues regarding the benefits and risks of ASA therapy in primary prevention of CVDs, for the older group in general and for individuals of all ages with diabetes. In this review, we summarize the benefits and risks related to ASA therapy by outlining the evidence for older patients and for patients with diabetes. There appear to be significant gaps in knowledge. The balance of benefits and risks is not well defined but ASA treatment seems to be unfavorable in many older patients.

Aspirin for primary prevention of cardiovascular events in the elderly: current status and future directions

The role of aspirin in the secondary prevention of occlusive cardiovascular events has now been well established. Given this, aspirin in primary prevention has been the focus of several large trials and subsequent meta-analyses over the past 3 decades, and yet the issue remains controversial. Recent studies in populations with high baseline risk - such as diabetics and those with asymptomatic peripheral arterial disease - have not found the expected benefits of aspirin on cardiovascular endpoints, which contrasts with earlier studies that reported a reduced relative risk for outcomes such as myocardial infarction and ischaemic stroke, but not for mortality. Furthermore, in healthy populations, the absolute risk reduction conferred by aspirin is small and needs to be balanced against the risk of a major haemorrhage. Older adults have a higher risk for cardiovascular events and therefore might represent the group in which aspirin for primary prevention could deliver the greatest absolute benefit, yet at the same time, the elderly bear an increased vulnerability to major haemorrhage, including haemorrhagic stroke. It is also not known whether older adults experience the same risk reduction from aspirin as middle-aged individuals. The current evidence base does not sufficiently clarify whether aspirin for primary prevention confers a meaningful net benefit in the elderly.

Stroke and its prevention in chronic kidney disease

This is a review of stroke mechanisms and management. The concept of stroke and transient ischemic attack and the recently proposed revision in definitions and controversies are discussed. We also discuss the use of antiplatelet and anticoagulant drugs for stroke due to carotid and cardiac disease.

Comparison of evidence on harms of medical interventions in randomized and nonrandomized studies

BACKGROUND

Information on major harms of medical interventions comes primarily from epidemiologic studies performed after licensing and marketing. Comparison with data from large-scale randomized trials is occasionally feasible. We compared evidence from randomized trials with that from epidemiologic studies to determine whether they give different estimates of risk for important harms of medical interventions.

METHODS

We targeted well-defined, specific harms of various medical interventions for which data were already available from large-scale randomized trials (> 4000 subjects). Nonrandomized studies involving at least 4000 subjects addressing these same harms were retrieved through a search of MEDLINE. We compared the relative risks and absolute risk differences for specific harms in the randomized and nonrandomized studies.

RESULTS

Eligible nonrandomized studies were found for 15 harms for which data were available from randomized trials addressing the same harms. Comparisons of relative risks between the study types were feasible for 13 of the 15 topics, and of absolute risk differences for 8 topics. The estimated increase in relative risk differed more than 2-fold between the randomized and nonrandomized studies for 7 (54%) of the 13 topics; the estimated increase in absolute risk differed more than 2-fold for 5 (62%) of the 8 topics. There was no clear predilection for randomized or nonrandomized studies to estimate greater relative risks, but usually (75% [6/8]) the randomized trials estimated larger absolute excess risks of harm than the nonrandomized studies did.

INTERPRETATION

Nonrandomized studies are often conservative in estimating absolute risks of harms. It would be useful to compare and scrutinize the evidence on harms obtained from both randomized and nonrandomized studies.

Previous antiplatelet therapy is an independent predictor of 30-day mortality after spontaneous supratentorial intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) constitutes 10% to 15% of all strokes. Despite several existing outcome prediction models for ICH, there are some factors with equivocal value as well as others that still have not been evaluated.

PATIENTS AND METHODS

All patients with first ever supratentorial ICH presenting to our institution between December 1995 and December 2002 were prospectively enrolled into the study. Patients with historic modified Rankin Scale > 2 and those under anticoagulant treatment or with multiple ICH were excluded. The following parameters were analyzed in 194 consecutive patients: age, gender, past history of hypertension, diabetes mellitus, hypercholesterolemia, past history of ischemic stroke, presence of ischemic heart disease or cardioembolic disease, current antiplatelet treatment, current alcohol overuse, smoking, Glasgow Coma Scale score (GSS) at admission, volume and location (deep or lobar) of ICH, ventricular extension, glycemia and temperature at admission, and leukoaraiosis. We correlated these data with the 30-day mortality identifying the independent predictors by logistic regression analysis.

RESULTS

Factors independently associated with 30-day mortality were: age, Glasgow Coma Scale score at admission, ICH volume, ventricular extension, glucose level at admission, and previous antiplatelet use.

CONCLUSIONS

Apart from the classical outcome predictors, the previous use of antiplatelet agents and the glucose value at admission are independent predictors of 30-day mortality in patients suffering a supratentorial ICH.

The UCSD Statin Study: a randomized controlled trial assessing the impact of statins on selected noncardiac outcomes

There has been persistent controversy regarding possible favorable or adverse effects of statins or of cholesterol reduction on cognition, mood and behavior (including aggressive or violent behavior), muscle function, and quality of life. The UCSD Statin Study seeks to ascertain the beneficial or adverse effects of statin cholesterol-lowering drugs on a set of noncardiac endpoints, including cognition, behavior, and serotonin biochemistry. The study will enroll 1000 subjects (minimum 20% female) of mixed ethnicity from San Diego. Subjects must be age 20 and older, postmenopausal if female, without known cardiovascular disease or diabetes, and with LDL-cholesterol between 115 and 190 mg/dl. Subjects will be randomized to a double-blind, placebo-controlled trial with assignment 1/3, 1/3, 1/3 to placebo, simvastatin 20 mg, or pravastatin 40 mg (equipotent LDL-cholesterol-lowering doses for drug arms with simvastatin and pravastatin chosen to represent the extremes of the lipophilicity spectrum) for 6 months of treatment followed by 2 months postcessation follow-up. Primary outcomes are cognition (cognitive battery), irritability/aggression (behavior measure), and serotonin (gauged by whole blood serotonin), assessed as the difference between baseline and 6 months, judging combined statin groups vs. placebo. Secondary outcomes include mood (CES-D and Wakefield depression inventory), quality of life (SF-12V), sleep (Leeds sleep scale, modified), and secondary aggression measures (Conflict Tactics Scale; Overt Aggression Scale, Modified). Cardiovascular reactivity will be examined in a 10% subset. As additional secondary endpoints, primary and selected secondary outcomes will be assessed by statin assignment (lipophilic simvastatin vs. hydrophilic pravastatin). "Reversibility" of changes, if any, at 2 months postcessation will be determined. If effects (favorable or unfavorable) are identified, we will seek to ascertain whether there are baseline variables that predict who will be most susceptible to these favorable or adverse noncardiac effects (i.e., effect modification).

Alcohol consumption and inflammatory markers in older adults: the Cardiovascular Health Study

OBJECTIVE

We sought to determine the relation of alcohol intake and systemic inflammation in a population-based sample of older adults.

METHODS AND RESULTS

As part of the Cardiovascular Health Study (CHS), 5865 adults aged 65 years and older reported their intake of beer, wine, and liquor. We determined white blood cell count (WBC), factor VIII coagulant activity (factor VIIIc), and levels of C-reactive protein (CRP), fibrinogen, and albumin as markers of systemic inflammation. Among participants without confirmed cardiovascular disease, alcohol consumption was inversely associated with WBC, factor VIIIc, and fibrinogen level, and positively associated with albumin concentration in multivariate analyses. We found no consistent modification of these results by sex, obesity, or beverage type. The relation of alcohol use and CRP levels was significantly modified by apoE genotype (P interaction 0.03), with a positive association among participants with an apoE4 allele (P = 0.05), but a trend toward an inverse association among those without an apoE4 allele (P = 0.15).

CONCLUSIONS

Alcohol intake is associated with lower levels of inflammatory markers in older adults free of cardiovascular disease.

Antiplatelet therapy in secondary stroke prevention

Stroke is the third leading cause of death in the United States. Antiplatelet agents are the mainstays of ischaemic stroke prevention. The therapies recommended for initial therapy include aspirin (50 - 325 mg) daily, the combination of aspirin (25 mg) and extended-release dipyridamole (200 mg) b.i.d., or clopidogrel (75 mg) daily. Ticlopidine 250 mg b.i.d. is approved for stroke prevention but is no longer a first-line therapy. This article reviews the literature on antiplatelet agents for secondary stroke prevention.

The effect of vasodilators on aspirin-induced antagonism of t-PA thrombolysis

Although i.v. t-PA has proven successful in reducing neurologic deficits in acute ischemic stroke, the disadvantages of a narrow therapeutic time window and the failure of thrombolysis in more than 50% of patients treated have necessitated an examination of adjuvant therapies to improve the rate of thrombolysis. Experimentally, the combination of aspirin therapy with t-PA has resulted in a paradoxical antagonism of thrombolysis. Reversal of this antagonism with nitric oxide (NO) donors suggested that aspirin may inhibit/ antagonize NO-related mechanisms. Using this rabbit model of thromboembolic stroke, this hypothesis is now expanded to compare two clinically relevant anti-hypertensive agents, atenolol (NO-dependent) and hydralazine (NO-independent), for their ability to improve t-PA-mediated clot lysis following aspirin pre-treatment. Thirty rabbits (10 per group) were pre-treated with aspirin (20mg kg(-1), i.v.) and then randomized to receive either vehicle, atenolol (20 microg kg(-1) h(-1), i.v.) or hydralazine (10 microg kg(-1) min(-1), i.v.) beginning 30 min following autologous clot embolization. All rabbits then received t-PA (6.3 mg kg(-1), i.v.) beginning 1 h after embolization, with completion of the protocol 4 h after embolization. Aspirin therapy reduced regional cerebral blood flow (rCBF) from 82.8m +/- 4.7 to 62.5 +/- 6.6 (n = 30; p = 0.0005). In the aspirin control group only 30% (3 of 10) rabbits demonstrated complete clot lysis, whereas the combined atenolol (60%) and hydralazine (70%) groups experienced a clot lysis rate of 65% (13 of 20 rabbits), similar to clot lysis rates previously observed with t-PA alone. In a separate series of experiments, all agents able to reverse aspirin antagonism of thrombolysis demonstrated an improvement in rCBF, suggesting a common mechanism for this diverse group of agents in reversing aspirin's antagonism of thrombolysis.

Complications of oral antiplatelet medications

One by-product of the flurry of large-scale clinical trials accompanying the emergence of drugs that inhibit platelet function is volumes of information chronicling the adverse effects of this class of medications. One aspect all antiplatelet drugs share is a propensity toward bleeding. Beyond that similarity, however, the different pharmacologic agents in this broad collection have few attributes in common. Aspirin, by virtue of its long history, has been studied most extensively, and has proven to be an exceptionally valuable therapy. However, the complicated adverse profile of this seemingly simple drug is commonly overlooked by practitioners and deserves clinical review. The thienopyridine class (including ticlopidine and clopidogrel) share certain peculiarities that continue to be clarified, including life-threatening thrombotic thrombocytopenia purpura. Dipyridamole is a veteran drug that is enjoying renewed attention as a prophylactic aid in preventing cerebrovascular events. One class, the oral platelet glycoprotein IIb/IIIa receptor inhibitors, has failed to find its way into clinical implementation due to an unfavorable balance between efficacy and adverse effect. This review summarizes the adverse profiles of each of these drug classes and draws on data gathered in large clinical studies.

Factors associated with healthy aging: the cardiovascular health study

OBJECTIVES

To identify factors associated with remaining healthy in older adults.

DESIGN

Longitudinal cohort study.

SETTING

Data were collected at the four Cardiovascular Health Study field centers.

PARTICIPANTS

5,888 participants age 65 years and older in the Cardiovascular Health Study.

MEASUREMENTS

Presence of chronic disease was assessed at baseline and over a maximum 7-year follow-up period. Participants who were free of chronic disease (no cardiovascular disease (CVD), chronic obstructive pulmonary disease, or self-reported cancer, except nonmelanoma skin cancer) at the baseline examination were then monitored for the onset of incident cancer, cardiovascular disease, and fatal outcomes.

RESULTS

A high proportion of these older adults was healthy at the initial examination and remained healthy over the follow-up period. Numerous behavioral factors were associated with continued health, including physical activity, refraining from cigarette smoking, wine consumption (women), higher educational status, and lower waist circumference. A number of CVD risk factors and subclinical disease measures were associated with continued health, including higher high-density lipoprotein (HDL) cholesterol, lack of diabetes, thinner common carotid intimal nmedial thickness, lower blood pressure, lower C-reactive protein, and higher ankle-arm blood pressure ratio. Among the behavioral factors, exercise, not smoking, and not taking aspirin remained significant predictors of health even after controlling for CVD risk factors and subclinical disease in older adults.

CONCLUSIONS

These data suggest that a number of modifiable behavioral factors (physical activity, smoking, and obesity) and cardiovascular risk factors (diabetes, HDL cholesterol, and blood pressure) are associated with maintenance of good health in older adults.

Heart disease in women

Women face a disparity in the evaluation and treatment of coronary artery disease, even though coronary artery disease is the leading cause of death for women in the United States. Primary care physicians play an important role in the identification and treatment of risk factors and comorbidities. It is their obligation to ensure that women receive equal and appropriate care, and to advocate for their patients.

Aspirin-associated intracerebral hemorrhage: clinical and radiologic features

OBJECTIVE

To identify the clinical and radiologic features of intracerebral hemorrhage (ICH) in aspirin users.

BACKGROUND

Although the benefits of aspirin outweigh its hemorrhagic risks for patients at high risk of vascular diseases, prolonged use of aspirin is associated with an increased risk of ICH.

METHODS

The authors enrolled consecutive patients with acute stroke who were admitted to a regional hospital from 1993 to 1998 into a stroke registry. From this registry, they identified all stroke patients who had ICH confirmed by CT scan and then selected those taking regular aspirin before ICH as the study group. For each study patient, they selected the immediate next two patients with ICH but not taking aspirin as controls.

RESULTS

The authors identified 58 aspirin users and 1193 nonusers among all patients hospitalized for ICH. From the group of nonusers, they selected 116 patients as controls. The locations of the hematoma were different (p = 0.002), with more lobar hematoma in the aspirin group (32.8%) than in the control group (10.3%). Prior cerebrovascular disease was the reason for taking aspirin in 37 (64%) patients but five patients had prior ICH.

CONCLUSIONS

The propensity for lobar hematoma in aspirin-associated ICH suggests its pathology may be somewhat different from spontaneous ICH among nonaspirin users. Further research to examine the risks and benefits of aspirin use in certain subgroups at risk of both thrombotic and hemorrhagic events is needed.

Stroke: antithrombin versus antiplatelet therapy

The success of thrombolytic therapy for acute stroke has demonstrated that neurologic outcome can be improved with timely treatment. However, the severely restricted use of thrombolytics has reinforced the need to develop alternative and complementary therapies. Antithrombin and antiplatelet agents represent promising therapeutic approaches for stroke management. Antiplatelet therapy has modestly improved outcome in both acute stroke (aspirin) and in secondary stroke prevention (aspirin with or without dipyridamole; adenosine receptor antagonists), although bleeding and other adverse events associated with antithrombin therapy have largely negated their potential benefit. These findings have prompted innovative solutions to the pharmacokinetic and pharmacodynamic challenges that are crucial to advancing these strategies for acute, primary and secondary stroke therapy. Currently, inhibitors of the platelet surface glycoprotein IIb/IIIa (GP IIb/IIIa, fibrinogen) receptor are being examined in clinical trials while antithrombin therapies focus on thrombin antagonists and inhibitors as well as inhibitors of Factor Xa. Further advances in stroke treatment will include combination therapies. Additionally, the successful design of future drug therapies will result from a more complete understanding of the activity of these agents not only on platelet function and the coagulation cascade, but also for their effects on the endothelium and within the brain parenchyma. The sum of these activities will allow for the maintenance of cerebral blood flow, blood-brain barrier integrity and neuronal function.

Outcome of moderate carotid artery stenosis in patients who are asymptomatic

PURPOSE

The incidence rate of disease progression and stroke after the diagnosis of a moderate (50% to 79%) carotid stenosis was determined by means of color-flow duplex scanning.

METHODS

During a 4-year period, 344 male veterans with moderate internal carotid artery stenoses, on one or both sides, were examined at regular intervals for a mean period of 25 months. Carotid color-flow scans were obtained semiannually. Clinical follow-up was performed to determine the incidence rate of amaurosis fugax, transient ischemic attacks, nonhemispheric symptoms, and strokes.

RESULTS

New neurologic symptoms developed in 75 patients (21.8%). Fifty-one (14.8%) had ipsilateral symptoms during follow-up: 18 amaurosis fugax (5.2%), 14 transient ischemic attacks (4%), 5 nonhemispheric symptoms (1.4%), and 14 strokes (4%). Twenty-four patients (6.9%) had contralateral symptoms: 20 strokes (5.8%) and 4 transient ischemic attacks (1.2%). Life-table analysis showed that the annual rate of ipsilateral neurologic events was 8.1%, and the annual rate of stroke was 2.1%. Seventy-five patients (22%) died in the follow-up period. Disease progression to 80% to 99% stenosis or occlusion occurred in 71 of 458 vessels (15.5%). The internal carotid arteries that showed evidence of disease progression had a significantly higher initial peak systolic velocity (251 vs 190 cm/s; P <.0001) and end diastolic velocity (74 vs 52 cm/s; P < 0.0001). Black patients and patients with ischemic heart disease were at a higher risk for disease progression. We could not identify any atherosclerotic risk factors that reliably predicted patients in whom future ipsilateral neurologic symptoms were more likely to develop. However, there was an increased risk of stroke associated with progression of disease.

CONCLUSION

Patients who are asymptomatic and who have moderate carotid stenoses are at significant risk for neurologic symptoms and death, but have a relatively low incidence rate of ipsilateral events. The initial flow characteristics in the stenotic vessel are predictive of future disease progression, but they are not helpful in identifying patients in whom symptoms will develop.